Initial commit

arm9/source/romBrowser/StateMachineTriggerChecker.h

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+#pragma once
+
+/// @brief Helper class for specifying state machine state transitions in an intuitive way.
+/// @tparam TState The state enum type.
+/// @tparam TTrigger The trigger enum type.
+template <typename TState, typename TTrigger>
+class StateMachineTriggerChecker
+{
+    const TState _fromState;
+    const TTrigger _trigger;
+    bool _isValid;
+    TState _newState;
+
+    TState _from;
+    TTrigger _fromTrigger;
+public:
+    /// @brief Constructs a StateMachineTriggerChecker for a state machine
+    ///        that is currently in state fromState and received the given trigger.
+    /// @param fromState The current state of the state machine.
+    /// @param trigger The received trigger.
+    explicit constexpr StateMachineTriggerChecker(TState fromState, TTrigger trigger)
+        : _fromState(fromState), _trigger(trigger), _isValid(false), _newState(fromState) { }
+
+    /// @brief Specifies the start of a state transition. Multiple triggers can be
+    ///        specified for a given from state.
+    /// @param from The start state of the following trigger definitions.
+    /// @return this
+    constexpr StateMachineTriggerChecker& In(TState from)
+    {
+        if (!_isValid)
+            _from = from;
+        return *this;
+    }
+
+    /// @brief Specifies the trigger for a state transition. Should be used
+    ///        after In has been used at least once.
+    /// @param trigger The trigger of the state transition.
+    /// @return this
+    constexpr StateMachineTriggerChecker& Trigger(TTrigger trigger)
+    {
+        if (!_isValid)
+            _fromTrigger = trigger;
+        return *this;
+    }
+
+    /// @brief Specifies the end state for a state transition. Should be used
+    ///        after every Trigger.
+    /// @param to The end state of the state transition.
+    /// @return this
+    constexpr StateMachineTriggerChecker& GoesTo(TState to)
+    {
+        if (!_isValid && _fromState == _from && _trigger == _fromTrigger)
+        {
+            _isValid = true;
+            _newState = to;
+        }
+        return *this;
+    }
+
+    /// @brief Ends the state transition definitions and returns
+    ///        the check result.
+    /// @param newState The new state for the state machine.
+    /// @return true if the received trigger was valid for the
+    ///         state of the state machine, or false otherwise.
+    constexpr bool Check(TState& newState) const
+    {
+        newState = _newState;
+        return _isValid;
+    }
+};